Set up the equations you know:
Since there are three consecutive numbers, lets say x,y,z, then they are found by adding one to the previous number. And since their product is 17550, multiplying them together is 17550.
x+1=y
y+1=z
x*y*z = 17550
The middle number is y, so plug it all in and get one equation in terms of y only.
x=y-1
z=y+1
(y-1)(y)(y+1) = 17550
Then multiply it out and get your answer